JSci.maths.statistics
Class WeibullDistribution

java.lang.Object
  JSci.maths.statistics.ProbabilityDistribution
      JSci.maths.statistics.WeibullDistribution

public final class WeibullDistribution
extends ProbabilityDistribution

The WeibullDistribution class provides an object for encapsulating Weibull distributions.

Constructor Summary

WeibullDistribution(double sh)
Constructs a Weibull distribution.

Method Summary

double	cumulative(double X) Cumulative Weibull distribution function.
double	getMean() Returns the mean.
double	getShapeParameter() Returns the shape parameter.
double	getVariance() Returns the variance.
double	inverse(double probability) Inverse of the cumulative Weibull distribution function.
double	probability(double X) Probability density function of a Weibull distribution.

Methods inherited from class JSci.maths.statistics.ProbabilityDistribution

checkRange, checkRange, findRoot

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WeibullDistribution

public WeibullDistribution(double sh)

Constructs a Weibull distribution.

Parameters:

sh - the shape.

Method Detail

getShapeParameter

public double getShapeParameter()

Returns the shape parameter.

getMean

public double getMean()

Returns the mean.

getVariance

public double getVariance()

Returns the variance.

probability

public double probability(double X)

Probability density function of a Weibull distribution. P(X) = s X^s-1 exp(-X^s).

Specified by:

probability in class ProbabilityDistribution

Parameters:

X - should be integer-valued.

Returns:

the probability that a stochastic variable x has the value X, i.e. P(x=X).

cumulative

public double cumulative(double X)

Cumulative Weibull distribution function.

Specified by:

cumulative in class ProbabilityDistribution

Parameters:

X - should be integer-valued.

Returns:

the probability that a stochastic variable x is less then X, i.e. P(x<X).

inverse

public double inverse(double probability)

Inverse of the cumulative Weibull distribution function.

Specified by:

inverse in class ProbabilityDistribution

Returns:

the value X for which P(x<X).